Bypass valve



z sheets-sneet 2 J c. TRAVILLA, JR, ET AL BYPASS VALVE Filed Jan. 22. 1942 Feb. 23, 1943;

INVENTORS JAMES C.TRAv|| A,JR. HARRY E. DOERR 7 BY M flTToP/v' Pl G. 5.

Patented Feb. 23, 1943 BYPASS VALVE James C. Travilla,

Jr., OverbrookHills, Pa., and

Harry E. Doerr, St. Louis, Mo.,assignors to General Steel Castings Corporation,

Granite City,

Ill.,a corporation of Delaware Application-January 22, 1942, Serial No. 427,748

Claims.

The invention relates particularly to the housing structure of by-pass valves associated with steam chests or piston valve chambers for cylinders of steam engines such as locomotives.

'Such by-pass valves involve small masses-of material relative to the steam chest with which they are associated and, when in operation, are subject to substantial variations in temperature tending to expand and contract th valve housing a different amount than the steam chest, and therefore the by-pass valve housing is likely to be fractured, or to have its joints loosened if it is of built-up construction, and the main objects of the present invention are to avoid such injury tothe valve and to reduce steam leakage and the expense of maintaining the Valve in satisfactory operating condition.

In the accompanying drawings illustrating the invention- Figure 1 is a section through the main cylinder of the locomotive engine and the associated steam chest with by-pass valve. The by-pass valve parts are in the position assumed when live steam under pressure is in the steam chest.

Figure 2 is a detailed illustration of a portion of the by-pass valve shown in Figure 1 in the position assumed when live steam is cut off from the steam chest, as when the locomotive is driftmg.

Figures 3, 4 and 5 are detailed sections through the'by-pass valve housing only, and each shows a different form of the invention.

In the assembly illustrated in Figures 1 and 2, the main cylinder I has the usual passages 2 leading from the steam chest 3 in which the piston valve 4 alternately connects the central steam receiving body of the steam chest with the ports at opposite ends of cylinder 1.

The by-pass valve includes a housing 5 formed integrally with the throttle valve chest 3. Bypass valves 6 are slidable in housing 5 between theposition shown in Figure l and the position shown in Figure 2. In the position shown in Figure 1, valves 6 close ports 7 leading from the piston valvesteam chest'into the by-pass valve housing, and the piston valve and main steam cylinder, with its piston 8, are operative to drive the locomotive. Live steam in steam chest 3 passes through pipe 9, a valve Ill, branch pipes I to the end portions of the by-pass valve housing, and seat valves 6 as illustrated in Figure 1.

When the steam pressure in steam chest 3 is relieved, as when the throttle is closed for drifting, by-pass valves 6 are moved outwardly by coil springs I 2 compressed between them so as to connect port I through the by-pass valve housing and prevent or relieveresistance'due to vacuum or pressure which would be created by the movement of piston 8 in the main cylinder.

When the locomotive is drifting, piston valve 4 in the steam chest movesthe same distances forward and backward as when the throttle is open and in certain positions of the stroke the piston valve closes alternately the live steamports 2' -between the steam chest and the main cylinder. This, however, does not close the passageways between the ends of the "main cylinder and the by-pass housing because the spaces. around the valve bushings l3 in the steamchest provide an open passageway between them.

This general assembly of the -by-pass valve and the other parts of the locomotive is in general use and in itself does not constitute the present invention.

To avoid the creation of undesirable strains in the by-pass valve housing, the latter is provided with one or more bulges or corrugations 14, which may expand andcontract to relieve the differences in expansion between thesteam chest and-the by-pass housing.

This arrangement makesit practicable to-form the by-pass housing and the steam chest'in a single casting without formingthe walls of excessiveli thick metal to withstand the "strains I set up by the expansion and contraction forces.

Figure 3 illustrates the use of a by-passvalve housing consisting of'a separately formed tube with its ends welded at W to the edgesof the valve cage portions of the casting which includes the steam chest 22. Tubes 26 are'bulged or corrugated at 23 similarly to the cast housing previously described. This arrangement "avoids breaking of the welded connections between the tubular housing and the opposing faces of the casting due to the difference in expansion between the parts subjected to the temperature of the live steam.

Figure 4 illustrates another form of the-invention in which the expansion valve housing 30 consists of a separately formedtube with substantially straight sides with its left hand end, forming a valve cage 3|, inserted in an annular opening in a cast metal projection 33 on the steam chest 32 and welded thereto as indicated at W.

The right hand end of housing 30 has a sliding fit in the corresponding projection 34 and a stuffing box is applied to the adjacent portions of the casting and tubular housing. The stuifing box includes a packing annulus 35 seated in a groove in the casting surrounding the by-pass housing tube, and a metal ring 36 with studs 31 for compressing the packing.

Figure illustrates another form of the invention in which the by-pass housing is formed by two sections 40 and 4| of substantially straight tubing, each section having its outer end welded at W" to the corresponding portion of the cast metal projection on the steam chest 43. The inner ends of sections 40 and 4| are spaced from each other and are provided with a stuffing box comprising a ring 44 fixed on tubular section 40 and a cooperating ring 45 slidably fitting on tubular section 4|, there being a packing annulus 46 between rings 44 and 45. Studs 41 draw the two rings together and provide for tightening of the packing against tube 4i.

In each form of the invention the end portions of the by-pass valve housing associated with the projections from the steam chest are relatively free of strain induced by the tendency of the by-pass valve housing to expand more rapidly than the heavier mass of metal comprising the steam chest and the main steam cylinder associated therewith. Hence the connections between the by-pass valve housing and the lateral projections on the steam chest, whether integral or welded, will not be ruptured nor will the side wall of the by-pass valve housing be fractured by the tendency of the ends of the bypass housing to move relative to each other because of expansion forces.

It will be understood that the detailed disclosure is intended to be illustrative and that variations in the structure other than those illustrated and described may be made by those skilled in the art without departing from the spirit of the invention, and the exclusive use of such modifications as come within the scope of the claims is contemplated.

What is claimed is:

1. A steam by-pass valve structure for an engine steam chest and including an elongated housing with end portions arranged for association with the steam chest, said structure being provided with yielding means for accommodating expansion and contraction of the steam chest relative to the housing.

2. In combination with a steam chest, having lateral projections rigid with the body thereof, and a by-pass valve including a housing having end portions provided with connections to corresponding steam chest projections and including means yielding to accommodate expansion and contraction of the steam chest relative to the valve housing.

3. In combination with with a steam chest, a by-pass valve structure with an elongated housing, the steam chest having spaced parts provided with ports leading to the end portions of said housing, said housing being provided with means spaced from said ports for accommodating expansion and contraction of the steam chest relative to the housing.

4. A locomotive steam valve housing consisting of a tubular structure with end portions arranged for connection to steam chest parts com prising relatively heavy masses of metal, said housing having a peripheral bulge in its wall between its end portions to accommodate expansion and contraction of the housing and thereby relieve the housing and steam chest parts of undue strain because of their connection to each other.

5. A one-piece cast structure comprising a steam chest and a by-pass valve housing, the end portions of said housing being secured to said steam chest and the intermediate portion of said housing comprising a substantially lighter mass of metal than said steam chest, said housing having a peripheral bulge intermediate its ends for accommodating expansion and contraction of said housing between its end portions.

6. A one-piece cast structure comprising a steam chest and a by-pass valve housing, said steam chest comprising a body portion for receiving a slide valve and lateral projections at the ends of said body portion, said valve housing being spaced from the body of said steam chest with its portions united with said projections, and said housing having a peripheral bulge in its side wall between its ends for accommodating different degrees of expansion and contraction of the steam chest and the valve housing thereby relieving these parts of undue strain because of their connection to each other.

7. A structure as specified in claim 2 in which the last means includes two relatively movable parts and a stufling box between them.

8. In combination, a steam chest having a body for receiving a piston valve and projections at the ends of said body, a by-pass valve housing with its end portions seated in said projections, one end portion being fixed to the corresponding projection, and a stuifing box between the other housing end portion and the other steam chest projection.

9. In combination, a steam chest having lateral projections at its ends, a by-pass valve housing comprising relatively movable sections each having an end portion seated in a respective steam chest projection and fixed thereto, and a stuffing box mounted between the other end portions of said sections and sildably receiving one of said sections to accommodate relative movement of said sections and to relieve said housing, sections and projections of undue strain because of their connection to each other.

10. In combination with a steam chest, a bypass valve structure with an elongated two-part housing, each part having an end portion rigidly affixed to the adjacent part of said steam chest, there being ports between said end portions and said steam chest, and a stumng box between the two parts of said housing accommodating expansion and contraction of the housing while said end portions remain fixed relative to said ports.

JAMES C. TRAVILLA, JR. HARRY E. DOERR. 

